This study examined the association of physical activity (PA) and sedentary behavior (SB) with chronic low back pain (CLBP) in older adults. Cross-sectional data were collected from 715 elders aged 65 years and over living in Dazaifu, Japan. CLBP was defined as pain that sustains more than 1-3 months within the past year. PA and SB were objectively measured using a triaxial accelerometer (Omron Healthcare, Active style Pro (HJA 350IT)). Participants were categorized into four groups (2 groups of PA×2 groups of SB) according to their levels of PA and SB (divided into 2 levels; low and high levels around the median). Logistic regression analysis was used to examine effect of PA/SB with CLBP. In the analyses, sex, age, body mass index, smoking, educational attainment, falls, handgrip strength, knee pain and non-locomotive activities were treated as potential confounders. The prevalence of CLBP was 35%. After adjustment of confounding factors, significantly higher risk of CLBP was shown only in Low PA/High SB group (odds ratio : 1.66, 95% confidence interval : 1.02-2.70), compared with that of the reference group (High PA/Low SB group). These results suggest that the combination of low PA and high SB might be the risk of CLBP. Future studies should try to clarify whether CLBP is a cause or a consequence of inactivity.